I found a tutorial once in the comm that has a picture on the background and in the foreground, there's a white layer with the use of the rounded rectangle tool showing the picture behind.
I'm sorry for not being specific and not providing an example.
I'm an icon artist from the Canadian west coast. I generally make icons of Harry Potter, all sorts of broadway things, Pirates of the Caribbean, and whatever else strikes my fancy at the time. Have a look around! I hope you enjoy my work. :)